What is a Calorie?

What is a calorie? And why is this term important when we’re talking about weight? A calories is the amount or measurement of heat necessary to raise the temperature of one gram of water one degree on the Celsius scale.

Excuse me? What does this have to do with why my pants won’t fit?

A calorie is also the unit of measurement of energy produced by food when it is oxidized, or used, in the body. Calories are like fuel for our bodies. We need them for our bodies to run. But if we pump more fuel into our bodies than we need for the amount of activity we do, the excess fuel just sits there. Your body will store this excess, unused fuel. It may store it as muscle, if you perform enough physical, muscle-building exercises such as weightlifting, or it may store it as fat.

You need to maintain a balance between the amount of calories you take in (food) and the amount of calories you use (exercise). You “burn” your body’s fuel – calories – when you perform physical activities, and you also burn calories just by sitting still, breathing and living each day.

If you perform enough physical activity, you may increase the amount of calories (or energy units) you burn each day and raise the amount of calories (or energy units) you need each day. So a person who is physically active can eat more calories each day without gaining weight, because this person uses the fuel he or she pumps in, instead of storing it as fat.

Each person is different when it comes to the amount of calories he or she needs each day. The amount of calories a person needs for fuel varies according to age, height, gender, amount of physical activity and other factors.

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  1. Tania Broadhead Says:

    I am having problems reading calories off NZ packaging, is the calorie amount the energy amount on the box? ie 202kj

  2. Liz Quilty Says:


    Kj is just another way of measuring energy, if you take the Kj and divide it by 4.2 you get the calories, Trey will list it in 2 or 3 ways. One is per 100gm, and one is per serving. Always check how many servings is in a packet, and how big a serving is also. ie, crackers may say 4200Kj per 100gm , divided by the 4.2 gives you calories , 1000 calories per 100gm. it may say something like 400Kj (around 100calories or just under) per serving, and 2 crackers per serving means each cracker is around 50 calories.
    For the most part, looking at the per 100gm column is good because whatever number it is, is the percentage (because its out of 100) so you can tell immediately what percentage is fat, carbs, protein, sodium etc. But generally speaking most times for calorie content you will want to check the serving size and energy content 🙂

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